Adaptive immune responses contribute to the pathogenesis of melanoma by facilitating immune evasion. V-domain Ig suppressor of T-cell activation (VISTA) is a potent negative regulator of T-cell function and is expressed at high levels on monocytes, granulocytes, and macrophages, and at lower densities on T-cell populations within the tumor microenvironment. In this study, 85 primary melanoma specimens were selected from pathology tissue archives and immunohistochemically stained for CD3, PD-1, PD-L1, and VISTA. Pearson's correlation coefficients identified associations in expression between VISTA and myeloid infiltrate (r = 0.28, p = 0.009) and the density of PD-1+ inflammatory cells (r = 0.31, p = 0.005). The presence of VISTA was associated with a significantly worse disease-specific survival in univariate analysis (hazard ratio = 3.57, p = 0.005) and multivariate analysis (hazard ratio = 3.02, p = 0.02). Our findings show that VISTA expression is an independent negative prognostic factor in primary cutaneous melanoma and suggests its potential as an adjuvant immunotherapeutic intervention in the future.
Keywords: Checkpoint inhibitor; Melanoma; Survival; Tumor microenvironment; Tumor-infiltrating lymphocytes; VISTA.